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Drum brake apparatus

a technology of drum brakes and cylinders, which is applied in the direction of mechanically actuated drum brakes, drum brakes, mechanical apparatus, etc., can solve the problems of reducing reducing and unable to stabilize the braking force, so as to improve the responsiveness of braking action and reduce the size of the operating force generating means

Active Publication Date: 2007-02-20
AKEBONO BRAKE IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a drum brake apparatus that can control the braking force based on the brake power, and can achieve stable braking and quick responsiveness. The apparatus includes a cam mechanism with a cam supporting plate, cam plates, and a swinging movement limiter to limit the range of movement of the cam plates and control the range of operation of the adjuster driving mechanism. The apparatus also includes a damper spring to alleviate impact when the cam plates come into abutment with the anchor pin. These features allow for a smaller operating force generator and improved responsiveness of the braking action.

Problems solved by technology

However, since the duo-servo type drum brake apparatus as described above is sensitive to variation in coefficient of friction of a lining of the brake shoe, there is a tendency that the braking force can hardly be stabilized, and hence there is a requirement for a device to stabilize the braking force.
Therefore, when a liquid-pressure piston or the like is used as the operating force generating means, there is a possibility to cause problems such as upsizing of the operating force generating means or lowering of the responsiveness of the braking action due to increase in the amount of used liquid in the initial stage of braking.

Method used

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Experimental program
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first embodiment

[0065]FIG. 1 is a front view showing a first embodiment of a drum brake apparatus according to the present invention.

[0066]The drum brake apparatus 1 according to the first embodiment is so-called duo-servo type drum brake apparatus, and includes a pair of brake shoes 3, 4 including a primary shoe 3 and a secondary shoe 4 disposed in a space in a substantially cylindrical drum, not shown, so as to oppose with each other, operating force generating means (a operating force generator) 6 disposed one of the opposite ends of the brake shoes 3, 4 for generating a shoe operating force for pressing the respective brake shoes 3, 4 against the drum when putting the service brake on, a cam mechanism 7 which is a shoe drive mechanism for transmitting an operating force generated by the operating force generating means 6, an adjuster unit 8 disposed between the other opposing end of the respective brake shoes 3, 4 having also a linking function for feeding an output power from the primary shoe ...

second embodiment

[0094]FIG. 5 to FIG. 7C show a second embodiment of the drum brake apparatus according to the present invention.

[0095]A drum brake apparatus 1A of the second embodiment is characterized in that a cam mechanism 7A for opening the pair of brake shoes 3, 4 outward is provided with a function for preventing over-adjusting of the adjuster unit 8.

[0096]In the drum brake apparatus 1A and the cam mechanism 7A, components common to the drum brake apparatus 1 and the cam mechanism 7 are designated by the same reference numerals or equivalent reference numerals, and description will not be made or simplified.

[0097]The adjuster unit 8 provided on the drum brake apparatus 1A adjusts the distance between the ends of the brake shoes 3, 4 according to the extent of abrasion of the lining of the respective brake shoes 3, 4, and is configured to adjust the distance between the ends of the brake shoes 3, 4 automatically by rotating an adjuster lever 82, the extremity of which is abutted against the ad...

third embodiment

[0108]FIG. 8 to FIG. 11 show a third embodiment of the drum brake apparatus according to the present invention.

[0109]A drum brake apparatus 1B in the third embodiment is characterized in that a damper spring 37 is built in a cam mechanism 7B for opening the pair of brake shoes 3, 4 outward.

[0110]In the drum brake apparatus 1B, the structure other than the cam mechanism 7B may be common to that of the first embodiment or of the second embodiment, and the common components are designated by the same reference numeral and description will not be made.

[0111]The structure of the cam mechanism 7B may be common to the cam mechanism 7 shown in the first embodiment other than the damper spring 37, and hence the common components are designated by the same reference numerals and description will be omitted.

[0112]When controlling the torque according to the brake power, the damper spring 37 provided on the cam mechanism 7B serves to alleviate an impact occurred when the anchor abutting arcuate...

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PUM

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Abstract

A cam mechanism 7 provided as a shoe drive mechanism includes a cam supporting plate 21 being loosely and rotatably fitted on an anchor pin 10 for receiving a shoe operating force, a first cam plate 23 rotatably connected to the cam supporting plate 21 at an outer cam supporting position which is a position shifted away from the anchor pin 10 radially outwardly of the drum, a second cam plate 25 rotatably connected to the cam supporting plate 21 at an inner cam supporting position which is away from the anchor pin 10 toward an operating force generator 6, so that a pair of brake shoes 3, 4 are opened outwardly by the separate cam plates 23, 25, respectively.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to a drum brake apparatus in which a highly effective and stable braking can be secured by controlling a pressing force of a brake shoe against a drum according to a brake power. More specifically, an improvement for realizing downsizing of operating force generating means or improvement of responsiveness of a braking action by reducing displacement in output from the operating force generating means.[0002]In the related art, various types of drum brake apparatuses in various forms are employed for braking the traveling of a vehicle. These drum brake apparatuses are classified into leading-trailing type, two-leading type, or a duo-servo type depending on the arrangement of brake shoes to be pressed against the inner peripheral surface of a substantially cylindrical drum.[0003]The duo-servo type drum brake apparatus is generally provided with a pair of brake shoes including a primary shoe and a secondary shoe disposed in ...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): F16D65/09F16D65/22F16D51/48F16D51/50F16D65/14
CPCF16D51/48F16D65/565F16D2121/02F16D2125/30F16D2123/00F16D2125/28F16D2121/14
Inventor MAEHARA, TOSHIFUMIMIYATA, KATSUHIROMITSUDE, YUKIMASAMUKASA, TAKAYUKINODA, TAKESHISAITOH, YOSHIAKI
Owner AKEBONO BRAKE IND CO LTD